Holy cow, that has to be one of the coolest things I have seen on the C64! I would just adore a full fledged dungeon crawler based on this. With items, puzzles, weapons, stats, doors, keys, ... doesn't even need to have a real story. I adore that minimalist approach that doesn't look minimalist, really. :3 How some colours, screen shakes can create such effects is very cool! :3
This is, basically, the stuff of dreams of old, and new, and I would like to spend endless nights exploring. :3